vga.c cleanups and changes:
* made lots of functions static, moved out of vga.h
* use constant PLANE_SIZE of 64K; always save 256K in standard VGA modes
* moved the state save to the end of the video init (init_vga_card)
  and don't let it clear the saved Linux video memory (from Stas)
* improved diagnostics
vc.c: repaired dosemu -c


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@712 7758b857-130e-0410-ab9c-d8735a528d18